Plug-in heater



FIG. 1 is a perspective view of a plug-in heater;

FIG. 2 is a front view of the plug-in heater of FIG. 1;

FIG. 3 is a right side view of the plug-in heater of FIG. 1;

FIG. 4 is a left side view of the plug-in heater of FIG. 1;

FIG. 5 is a back view of the plug-in heater of FIG. 1;

FIG. 6 is a top view of the plug-in heater of FIG. 1; and,

FIG. 7 is a bottom view of the plug-in heater of FIG. 1.

The broken lines and the areas within them depict portions of the plug-in heater that form no part of the claimed design. 

CLAIM The ornamental design for a plug-in heater, as shown and described. 